Grain dryer with improved grain deflector

ABSTRACT

A concurrent-countercurrent flow, column type grain dryer having an enclosed bin with a wet grain inlet at the top and a dry grain outlet at the bottom includes means for introducing a concurrent flow of hot air as a drying medium for the grain. Means are also provided at the bottom of the bin to introduce a countercurrent flow of cool air through the grain. Intermediate the means for introducing the hot and cool air is an exhaust for the heating and cooling air. The improvement of this invention comprises grain deflectors positioned intermediate the hot air inlet ducts and the exhaust ducts. The deflectors initiate cross flows of grain to prevent channeling of the grain and the hot air flow and to insure uniform heating and drying of the grain.

[11] 3,710,449 51 Jan. 16, 1973 United States Patent [191 Rathbun A Primary ExaminerFrederick L. Matteson Assistant ExaminerI-Iarry B. Ramey D E v O R m mR IO WT C E mu RE DD NN II AA RR GG m Att0rneyMolinare, Allegretti, Newitt & Witcoff [57] ABSTRACT A concurrent-countercurrent flow, column type grain [22] Filed:

[21] Appl.No.: 104,305

dryer having an enclosed bin with a wet grain inlet at the top and a dry grain outlet at the bottom includes means for introducing a concurrent flow of hot air as a drying medium for the grain. Means are also provided at the bottom of the bin to introduce a countercurrent Ne #ms L f C d Std I ll U.mF 1]] 2 00 555 [.lzl

' flow of cool air through the grain. Intermediate the V References Cited UNITED STATES PATENTS 2/1967 Graham... 4/1955 Oholm means for introducing the hot and cool air is an exhaust for the heating and cooling air. The improvement of this invention comprises grain deflectors positioned intermediate the hot air inlet ducts and the ,ex-

haust ducts. The deflectors initiate cross flows of grain ....34/65 X toprevent channeling of the grain and the hot air flow and to insureuniform heating and drying of the grain.

8 Claims, 3 Drawing Figures PATENTEUJAH 16 I975 SHEET 1 [1F 2 INVENTOR. CHARLES H. RATHBUN BY ,4 MW 7 A),

ATTOR PATENTEUJAH 16 I975 SHEET 2 BF 2 Mist/f ATTO NEYS INVENTOR. CHARLES H. RA THBUN GRAIN DRYER WITH IMPROVED GRAIN DEFLECTOR BACKGROUND OF THE INVENTION In some prior art systems, grain is heated quickly to a maximum temperature. It is then immediately and quickly cooled by exposure to air. This immediate temperature change often results in stress cracking and shattering of the grain. Once cracking occurs, very little moisture removal can be accomplished. Moreover, the grain is not in a condition acceptable to many grain elevators and processors.

Various other means have been disclosed which are supposed to heat and dry the grain uniformly while avoiding stress cracking and shattering. For example, in cross flow column type grain dryers, air is transversely forced through the downward moving grain in an attempt to evaporate moisture. Unfortunately, cross flow dryers do not normally provide a uniform air flow and heating path. Thus, the grain is dried unevenly by this type of device.

Counterflow drying systems force drying air through the grain in a direction opposite to the direction of grain travel. This type of system causes the dried grain at the bottom of the bin to be exposed to the hottest air, and the wet grain at the top to be exposed to the cooler air. This is apparently the most efficient drying method; however, the quality of the dried grain is not always acceptable since the grain tends to crack when dried according to this method.

A third method for drying grain provides for concurrent flow; that is, hot drying air travels downward in the same direction as the flowing grain. A modification of this method provides an additional countercurrent flow of cool air in a direction opposite to the direction of grain travel. Air exhaust means are also provided intermediate the hot air inlet and cool air inlet. In this manner, the hottest air is used at the point where it does the most good; that is, where the grain is the wettest and coolest, and as the two travel together, the air heats and dries the grain while the grain gradually cools the air. The tempered counterflow of cooling air cools the grain before it reaches the grain outlet at the bottom of the bin. Graham U.S. Pat. No. 3,302,297 or Oholm U.S. Pat. .No. 2,706,343 illustrate typical con- SUMMARY OF THE INVENTION In a principal aspect, the present invention relates to a grain dryer of the type having an enclosed bin with a wet grain inlet at its top and dry grain outlets at the bottom, a plurality of spaced horizontal hot fluid inlet ducts are provided for directing a fluid drying medium downward through a bed of grain in the bin. Below the dryer of the present invention.

hot fluidinlets are a plurality of spaced horizontal cold fluid inlet ducts for directing a fluid cooling medium upward and through the same bed of grain. The cold fluid inlet ducts are spaced from one another to provide a plurality of grain discharge outlets. Means are provided for adding wet grain through the wet grain inlet, and means are provided for removing dry grain from the grain outlets. Intermediate thefluid inlet ducts is an exhaust duct for receiving and exhausting the drying fluid mediums flowing from both the hot and cold fluid inlet ducts. Means are also supplied for providing hot fluid to the hot fluid inlet ducts and cold cold fluid inlet ducts.

The improvement comprises grain deflector means positioned intermediate the hot fluid inlet ducts and the fluid exhaust ducts. The deflector means deflect downward flowing grain and to some extent the drying medium to thereby provide at least partial cross flow drying conditions in the drying zone intermediate the hot fluid inlet ducts and the fluid exhaust ducts. An object of the invention is to provide a grain dryer including means to eliminate wet pockets which might otherwise be formed in the drying grain.

It is, thus, a further object of the present invention to provide an improved grain dryer.

Another object of the present invention is to provide a grain dryer which eliminates hot air flow channels least in part, cross flow of grain and hot air and thereby obtain uniform heating and drying.

These and other objects, advantages and features of the present invention will be set forth in greater detail below.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description which follows, reference will be made to the drawing comprised of the following FIGURES:

FIG. I is a cross-sectional view of a typical prior art column type, concurrent-countercurrent flow grain dryer;

FIG. 2 is a cross-sectional view of the improved column type, concurrent-countercurrent flow grain dryer embodying the present invention; and

FIG. 3 is a sectional exploded view of the improved column type, concurrent-countercurrent flow grain DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, like numbers refer to like parts and, although FIG. 1 represents prior art, the similar components are similarly numbered in FIGS; 2 and 3 which illustrate the improvements of the invention.

Referring to FIGS. 1, 2 and 3, there is shown a crosssectional view of a concurrent-countercurrent flow column type grain dryer 10. Grain dryerlO includes a completely enclosed bin 11 having a bottom consisting of downward'sloping surfaces 12 and 14, side walls 16 and 17, end walls 18 and 19 and a top 20 consisting of upward sloping surfaces 21 and 22. The bin 11 is supfluid to the ported on a stand 23. At the point where the upward sloping surfaces 21 and 22 meet, a wet grain inlet auger 24 is located whereby wet grain is introduced uniformly into the top of the bin 11. A dry grain outlet auger 26 is located at the bottom of bin 11 at the juncture of downward sloping surfaces 12 and 14. The augers 24 and 26 are parallel with the earth, with each other and with the side walls 16 and 17.

A plurality of five parallel spaced hot air ducts 28 (28A-28E) located near the top of bin 11 are parallel to the augers 24 and 26 and walls 16 and 17. Ducts 28 extend through end wall 18, center support wall 27 to wall 19, as shown in FIG. 3. Ducts 28 include vertical side walls 30 and 32, a peaked top 34, and an open underside 36. Ducts 28 lie in a common horizontal plane.

A plurality of six enclosed parallel spaced cool air ducts 38 (38A-38F) are located below the hot air inlet ducts 28 and above grain outlet auger 26. Ducts 38 are parallel to the hot air ducts 28 and extend through end wall 18 to wall 19 in the same manner as ducts 28. Ducts 38A and 38F are semi-triangular in cross section, whereas ducts 38B38E are triangular in cross section. Adjacent cold air inlet ducts are spaced from one another to define five grain discharge outlets 40A-40E. Grain discharge outlets 40A-40E are positioned directly vertically below each hot inlet duct 28A-28E, respectively. Metering rolls 42A-42E are located below grain discharge outlets 40A40E respectively, to control the gravitational flow of grain downward through the dryer. Intermediate the hot air inlet ducts 28 and cold inlet ducts 38 are a plurality of exhaust ducts 44 positioned transversely to the hot and cool inlet ducts 28 and 38. Ducts 44 serve to exhaust the hot and cool air introduced by inlet ducts 28 and 38, respectively.

The prior art device of FIG. 1 operates as follows: Grain inlet auger 24 is set in operation and proceeds to fill the bin 11 with wet grain. When the bin is filled, metering rolls 42 begin to operate and slowly allow grain to gravitate to the bottom of the bin 11. Hot air is introduced through hot air ducts 28 and flows concurrently with the grain and out of the exhaust ducts 44. As the grain continues to flow downward cool air from cool air ducts 38 flows countercurrently to the grain flow and exits at exhaust ducts 44. Hence, the areas between the hot air ducts and the exhaust ducts is called the drying section, and the area between the cool air ducts and the exhaust ducts is called the cooling section.

In FIGS. 2 and 3, the improvement of the present invention is illustrated. The improvement comprises grain deflectors 60 (60A-60F) extending between end walls 18 and 19. Grain deflectors 60 are located in the drying section parallel to, extending the same length as, and below the hot air inlet ducts 28. The deflectors 60 and ducts 38 are analogously positioned. That is, deflector 60A is positioned vertically over duct 38A and serves to divert grain inwardly from a position between bin side wall 16 and hot air duct 28A to a position substantially directly beneath duct 28A. Similarly, deflector 60B directs grain from a position between ducts 28A and 283 to a position beneath duct 28A or 28B. Deflectors 60A and 60F are fastened to the side walls 16 and 17, respectively, whereas deflectors 60E-60E are attached to end walls 18 and 19 and are suspended at substantiallytheir midpoint by a strap 29 (298-2915) attached to center support wall 27. Thus, there is a one-to-one correspondence between the deflectors 60 and cold ducts 38. In addition, the grain passages between deflectors 60 are positioned substantially directly vertically over discharge passages 40.

As indicated above, the deflectors 60 are divided into two groups: Group 1 side deflectors 60A and 60F; Group 2 center deflectors 60B-60E. The side deflectors 60A and 60F extend from their respective side walls 16 and 17 inwardly and then downwardly to the top of the exhaust ducts 44. The side deflectors 60A and 60F are perforated and, thus, do not restrict the cross-sectional area of the dryer 10 in the region immediately above the exhaust ducts 44. Another very important feature of the side deflectors 60A and 60F is the guidance of grain from walls 16 and 17 to a position beneath the hot ducts 28A and 28E, respectively.

Center deflectors 60B-60E include a first perforated, inclined surface 708-7015 and a second perforated, inclined surface 71B-71E, respectively, joined at an apex. The apex of each deflector 60 is in the same horizontal plane and is spaced below the lower reach of side panels 30 and 32 by a distance at least equal to the distance between adjacent ducts 28. Thus, grain flow is unhampered by any restriction in the vicinity of deflector 60 or duct 28.

The surfaces and 71 are inclined at substantially the angle of repose of the grain which is being dried. Typically, this may be 42 to 43 for wet corn. The sur faces 70B70E and 718-7113 are also perforated with openings that permit passage of air flow only. The grain is deflected and does not pass through the openings. Thus, perforations of the same dimensions as utilized for the exhaust outlet 44 and inlet 38 are appropriate. Side panels 72 and 73 extend downwardly from the surfaces 70 and 71, respectively, to prevent grain from flowing and clogging the space beneath surfaces 70 and 71. Of course, as previously mentioned, side panels 73A and 72F extend downwardly to ducts 44.

In a typical dryer wherein the bin is 8 feet wide and 20 feet long and wherein the five inlet ducts 28 are approximately l2 inches wide and are spaced 5 inches from each other (ducts 28A and 28E being spaced about 7 inches from walls 16 and 17, respectively), the adjacent center deflectors 60B, 60C, 60D and 60E are 7 to 8 inches wide and are spaced from one another by approximately 9 to l0 inches. Side deflectors 60A and 60F have their walls 73A and 72F spaced from walls 16 and 17, respectively, by approximately 3 to 4 inches. Thus, the spacing between deflectors 60A and 608 or 60E and 60F is somewhat greater than the spacing between center deflectors 60E-60E. As can be seen by an inspection of the cross-sectional view of FIG. 2, the grain flow rate adjacent the ducts 28 is slightly less than the grain flow volume adjacent deflectors 60. This results since the horizontal cross-sectional area of grain adjacent ducts 28 is slightly greater than the horizontal cross-sectional area adjacent deflectors 60.

FIG. 3 shows a sectioned, exploded view of the grain dryer. In operation, the bin 11 is filled with grain via feed conveyor 61 feeding grain inlet auger 24. As the metering rolls 42 begin operating, the fan 62 is rotated, thereby forcing air through duct means to hot inlet duct opening 64 and cold inlet duct openings 68. Inlet ducts 28 have a heating unit 65 comprised of an LP gas vaporizer and burners located near opening 64 to heat the air flowing therein. Hot air inlet ducts 28A-28E have baffles 66 positioned along their length to deflect the flow of hot air. Air generated by fan 62 passes over unit 65 into ducts 28A-28E and downward via baffles 66 into bin 11. The baffles 66 are positioned along the length of duct 28 so that each successive baffle extends vertically upward into the duct 28 for a greater distance than the preceding baffle 66 situated more closely to unit 65. Thus, the height of baffles 66 varies from a low baffle at the inlet end of duct 28 to high baffle at the opposite end of ducts 28 to insure uniform air distribution into bin 11.

The grain deflectors 60 are located directly beneath the unperforated hot air inlet ducts 28 and are positioned between the space defined by adjacent ducts 28. The deflectors 60 can be of sheet metal construction, perforated to allow some of the heat (as at 60B in FIG. 3) to flow therethrough. Beneath the deflectors 60 is shown one exhaust duct 44 into which the hot drying air flows. These ducts 44, only one of which is shown, are also of sheet metal construction with perforations to allow the air to flow therein. Shown beneath the exhaust ducts 44 are cool air inlet ducts 38 perforated to allow the flow of cool air introduced by fan 62. The cool air flows upward through the downward moving grain to the exhaust ducts 44.

As grain flows between the hot inlet ducts 28, it is deflected by grain deflectors 60 and is provided with horizontal velocity and direction components. The

- straight downward flow of grain found in the prior art is altered considerably. Likewise, the dryer is no longer strictly a concurrent-countercurrent dryer since cross flow components of velocity and displacement are provided to the grain. The grain deflectors 60 also serve to set up some cross flows of hot air, thereby eliminating the straight downward flow of hot air from inlet duct 28 to exhaust duct 44. This continuous across flow of grain and to some degree a cross flow of hot air eliminates hot air flow channeling and insures more uniform drying of grain throughout the drying section.

As a result of this construction and the elimination of channeling, the moisture content of dried grain is substantially uniform. For example, using the prior art configuration in a dryer having an 8' X 20' horizontal cross section with a dimensional arrangement for ducts 28, 38 and 44 set forth above and attempting to reduce moisture content of the grain from 25 to percent resulted in providing grain having a large range of moisture content (Le. a blending of grain having various moisture contents of approximately 7 percent).

This was determined by taking numerous samples of dried grain at various positions along the length of the metering rollers 42. With the improvement of the present invention utilizing deflectorsof the dimensions described above, the range of blending or moisture content of the dried grain was reduced by about onehalf to approximately 4 percent.

The addition ,of grain deflectors 60, through an economical improvement, has substantially improved the concurrent-countercurrent flow, column type grain dryer. The cross flow of grain and hot air which the deflectors set up in ,the drying section eliminates straight downward channeling, wet pockets and over heating of a small amount of grain. Cross flow of both grain and to some extent hot air flow insures uniform heating and drying, thus eliminating waste due to uneven drying systems of the past.

What Is Claimed Is:

1. In a grain dryer of the type having an enclosed bin with side walls, a top and a bottom, a wet grain inlet at the top, a plurality of parallel, uniformly spaced, horizontal hot fluid inlet ducts positioned adjacent the top and beneath the grain inlet for directing a fluid drying medium downward through a bed of grain in said bin, a plurality of parallel, horizontal cold fluid inlet ducts parallel to said hot fluid inlet ducts for directing a fluid cooling medium upward through a bed of grain, adjacent ones of said cold fluid inlet ducts spaced to provide a plurality of grain discharge outlets from said bin, means for adding wet grain through said wet grain inlet, means for withdrawing dry grain from said grain outlets, a plurality of horizontal, parallel exhaust ducts intermediate and transverse to said hot and cold fluid inlet ducts to receive and exhaust fluid medium flowing from said hot inlet ducts in a concurrent direction to grain flow and to receive and exhaust cold fluid medium flowing from said cold inlet ducts in a countercurrent direction to grain flow, means for providing hot fluid to said hot inlet ducts and cold fluid to said cold inlet ducts, and wherein each of said hot fluid inlet ducts comprise a duct enclosed on three sides and with an open bottom for flow of air concurrent withgrain, said hot fluid inlet ducts being in a substantially common plane and spaced uniformly in said bin, the improvement comprising:

a plurality of parallel, horizontal grain deflectors positioned in a plane intermediate said hot inlet ducts and said exhaust ducts, one of said deflectors positioned below and between each pair of parallel hot fluid inlet ducts and parallel with said hot fluid inlet ducts to deflect grain flowing downward between said hot fluid inlet ducts to a position substantially directly below said hot inlet ducts thereby providing cross flow drying within the zone intermediate said hot inlet ducts and said exhaust ducts in addition to concurrent flow drying.

2. The apparatus of claim 1 wherein each of said grain deflectors comprise a pair of surfaces formed of perforated material and joined together at an apex line parallel to said hot fluid inlet ducts.

3. The apparatus of claim 2 wherein grain deflector surfaces are inclined at substantially the angle of repose of said grain.

4. The apparatus of claim 1 wherein said grain deflectors are separated from one another by a distance no less than the distance between adjacent hot inlet ducts.

5. The apparatus of claim 1 wherein pairs of parallel grain deflectors define a grain flow passage substantially vertically above one of said grain outlet flow passages between said cold fluid inlets.

6. The apparatus of claim 1 wherein said deflectors are spaced vertically beneath said hot fluid inlet ducts by distance at least equal to the spacing of adjacent hot fluid inlet ducts.

7. The apparatus of claim 1 including opposite side deflectors attached to said side walls and a plurality of center deflectors intermediate said side deflectors.

8. The apparatus of claim 1 wherein said grain deflectors are at least in part perforated for flow of fluid therethrough. 

1. In a grain dryer of the type having an enclosed bin with side walls, a top and a bottom, a wet grain inlet at the top, a plurality of parallel, uniformly spaced, horizontal hot fluid inlet ducts positioned adjacent the top and beneath the grain inlet for directing a fluid drying medium downward through a bed of grain in said bin, a plurality of parallel, horizontal cold fluid inlet ducts parallel to said hot fluid inlet ducts for directing a fluid cooling medium upward through a bed of grain, adjacent ones of said cold fluid inlet ducts spaced to provide a plurality of grain discharge outlets from said bin, means for adding wet grain through said wet grain inlet, means for withdrawing dry grain from said grain outlets, a plurality of horizontal, parallel exhaust ducts intermediate and transverse to said hot and cold fluid inlet ducts to receive and exhaust fluid medium flowing from said hot inlet ducts in a concurrent direction to grain flow and to receive and exhaust cold fluid medium flowing from said cold inlet ducts in a countercurrent direction to grain flow, means for providing hot fluid to said hot inlet ducts and cold fluid to said cold inlet ducts, and wherein each of said hot fluid inlet ducts comprise a duct enclosed on three sides and with an open bottom for flow of air concurrent with grain, said hot fluid inlet ducts being in a substantially common plane and spaced uniformly in said bin, the improvement comprising: a plurality of parallel, horizontal grain deflectors positioned in a plane intermediate said hot inlet ducts and said exhaust ducts, one of said deflectors positioned below and between each pair of parallel hoT fluid inlet ducts and parallel with said hot fluid inlet ducts to deflect grain flowing downward between said hot fluid inlet ducts to a position substantially directly below said hot inlet ducts thereby providing cross flow drying within the zone intermediate said hot inlet ducts and said exhaust ducts in addition to concurrent flow drying.
 2. The apparatus of claim 1 wherein each of said grain deflectors comprise a pair of surfaces formed of perforated material and joined together at an apex line parallel to said hot fluid inlet ducts.
 3. The apparatus of claim 2 wherein grain deflector surfaces are inclined at substantially the angle of repose of said grain.
 4. The apparatus of claim 1 wherein said grain deflectors are separated from one another by a distance no less than the distance between adjacent hot inlet ducts.
 5. The apparatus of claim 1 wherein pairs of parallel grain deflectors define a grain flow passage substantially vertically above one of said grain outlet flow passages between said cold fluid inlets.
 6. The apparatus of claim 1 wherein said deflectors are spaced vertically beneath said hot fluid inlet ducts by distance at least equal to the spacing of adjacent hot fluid inlet ducts.
 7. The apparatus of claim 1 including opposite side deflectors attached to said side walls and a plurality of center deflectors intermediate said side deflectors.
 8. The apparatus of claim 1 wherein said grain deflectors are at least in part perforated for flow of fluid therethrough. 